The by-polls are being held in Radhakrishnan Nagar in Tamil Nadu, Aruvikkara in Kerala, Chokpot in Meghalaya, Pratapgarh and Surma in Tripura, and Garoth in Madhya Pradesh.

The focus in Saturday's by-poll will be on Radhakrishnan Nagar in Tamil Nadu as Chief Minister J. Jayalalaithaa is in the fray there seeking election to the state assembly.

The contest in Radhakrishnan Nagar is expected to be easy for Jayalalithaa as opposition parties like the DMK, the PMK and the MDMK have opted to stay out of the fray.

Jayalalithaa, who was elected from Srirangam in May 2011, lost her seat and the chief minister's post after a trial court's verdict holding her guilty in a disproportionate assets case.

The Karnataka High Court later upheld her appeal and acquitted her of all charges. Jayalalithaa was again sworn in as chief minister last month.

In Aruvikkara, the Bharatiya Janata Party -- which is yet to open its account in the 140-member Kerala assembly -- has fielded 85-year-old former union minister O. Rajagopal. The by-poll was necessitated following the death of assembly speaker G. Karthikeyan in March.